Method and apparatus for generating and using enhanced tree bitmap data structures in determining a longest prefix match

a tree bitmap and prefix technology, applied in the field of communication and computer systems, can solve the problems of two internal nodes accessing two internal nodes, and the internal nodes are scattered across multiple memory banks

US20050157712A1Active Publication Date: 2005-07-21CISCO TECH INC
31 Cites 271 Cited by

Patent Information

Authority / Receiving Office
US · United States
Patent Type
Applications(United States)
Current Assignee / Owner
Publication Date
2005-07-21

Smart Images

  • Figure 1
    Figure 1
  • Figure 2
    Figure 2
  • Figure 3
    Figure 3
Patent Text Reader

Abstract

Methods and apparatus are disclosed for generating and using an enhanced tree bitmap data structure in determining a longest prefix match, such as in a router, packet switching system. One implementation organizes the tree bitmap to minimize the number of internal nodes that must be accessed during a lookup operation. A pointer is included in each of the trie or search nodes to the best match so far entry in the leaf or results array which allows direct access to this result without having to parse a corresponding internal node. Moreover, one implementation stores the internal node for a particular level as a first element in its child array. Additionally, one implementation uses a general purpose lookup engine that can traverse multiple tree bitmaps or other data structures simultaneously, and perform complete searches, partial searches, and resume partial searches such as after receiving additional data on which to search.
Need to check novelty before this filing date? Find Prior Art

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This is a divisional of application Ser. No. 10 / 161,504, filed May 31, 2002, and hereby incorporated by reference.FIELD OF THE INVENTION

[0002] This invention especially relates to communications and computer systems; and more particularly, the invention relates, but is not limited to generating and using enhanced tree bitmap data structures in determining a longest prefix match, such as in a router, packet switching system, or other communications or computer system. BACKGROUND OF THE INVENTION

[0003] The communications industry is rapidly changing to adjust to emerging technologies and ever increasing customer demand. This customer demand for new applications and increased performance of existing applications is driving communications network and system providers to employ networks and systems having greater speed and capacity (e.g., greater bandwidth). In trying to achieve these goals, a common approach taken by many communications p...

Examples

Embodiment Construction

[0038] Methods and apparatus are disclosed for generating and using enhanced tree bitmap data structures in determining a longest prefix match, such as in a router, packet switching system, or other communications or computer component, device, or system. Embodiments described herein include various elements and limitations, with no one element or limitation contemplated as being a critical element or limitation. Each of the claims individually recites an aspect of the invention in its entirety. Moreover, some embodiments described may include, but are not limited to, inter alia, systems, networks, integrated circuit chips, embedded processors, ASICs, methods, and computer-readable medium containing instructions. The embodiments described hereinafter embody various aspects and configurations within the scope and spirit of the invention, with the figures illustrating exemplary and non-limiting configurations.

[0039] As used herein, the term “packet” refers to packets of all types or ...